The present invention relates generally to agricultural machinery and, more particularly, to improvements for measuring the throughput of material on conveyors.
The invention specifically relates to an apparatus for measuring where the conveyer blades carrying the material (in particular, cereal grains) are continuously moved in a conveyer shaft. A photoelectric device is mounted on the shaft so that its light beam is aligned substantially parallel to the preferably flat surfaces of the blades. A signal processor determines the distance between the top edge of the material and the passing blade carrying the material from the light-dark periods of the signal. The signal processor determines the apparent volume of material on each blade, taking into account the spacing of the blades, the thickness of the blades, and the cross-sectional area of the shaft.
An apparatus of this general type is known from German patent 30 45 728 C2. Conveyer blades carrying the harvested material (in particular, cereal grains) are aligned approximately perpendicularly to the walls of a rectangular conveyer shaft. An endless chain continuously pulls the conveyor blades through the shaft. The surface of the layer of grain on the blade is approximately horizontal. The shaft is mounted on a combine harvester and is usually inclined to the vertical in the plane of the chain. A photoelectric device is mounted in parallel with the blades and is effective between the side walls of the shaft. The dark period of the light beam for the pass of each loaded blades is measured. The height of the load is determined, taking into account the dark period due to the thickness of the blade itself. The volume of grain being conveyed is determined by multiplying the height by the area of the shaft or a function of the shaft geometry. This apparatus only works relatively accurately when the combine harvester is on a horizontal surface so that the conveyer is in its normal position and when the blades are sufficiently full. However, if the conveyer is transversely or longitudinally inclined relative to its normal position, such as when it is being moved on a slope or at different loadings of the grain tank or when crossing loose earth, its operation is impaired and the computed result is extremely inaccurate. Under such circumstances, the measurement of the volume of grain being conveyed is usually too high.
Furthermore, it is known from German patent 195 44 057 A1 that in order to correct the weight of corn being conveyed in an inclined conveyer, where the weight is being systematically underestimated by a weighing sensor, one may calculate the true quantity of conveyed corn by means of a signal from an inclinometer functioning in two directions. However, this weighing apparatus for the conveyer is complex and the need to decouple the drive mechanism therefrom is also technically complex.
Moreover, it is known from European patent 0 702 891 A1 to associate location data, speed signals and throughput time constants with continuously measured amounts in a harvesting machine so as to establish a harvesting cadastre. Here, one falls back on stored or externally defined standard litre-weights with respect to average quality and average moisture content for the different sorts of cereals. The harvest production performance and the relative losses associated therewith are continuously displayed on an indicator.
An object of the present invention is overcome one or more of the deficiencies noted above.
Another object is to provide an improved measuring apparatus having improved accuracy.
Still another object is to provide an improved apparatus of the type described and having a simplified construction.